Hydrofluorocarbons (HFCs), such as pentafluoroethane (HFC-125), are non-chlorine containing fluorocarbons that can be used as a refrigerant, blowing agent, propellant, fire extinguishing agent, sterilant carrier gas, among other valuable uses. By being non-chlorine containing, HFCs are believed to have less effects upon the earth's ozone layer.
One method for making pentafluoroethane comprises chlorofluorinating perchloroethylene to produce a mixture comprising trichlorotrifluoroethane (CFC-113), dichlorotetrafluoroethane (CFC-114), and dichlorotrifluoroethane (HCFC-123), along with by-product HCl. After removing at least some HCl and trichlorotrifluoroethane, the remaining mixture can be fluorinated by various processes thereby producing a mixture containing pentafluoroethane (HFC-125), chloropentafluoroethane (CFC-115), by-product HCl and lesser amounts of other fluorinated and chlorinated compounds, e.g., chlorotrifluoromethane (CFC-13) and trifluoromethane (HFC-23).
Certain halocarbons have been separated using conventional distillation. Another distillation method relates to extractive distillation. Procedures which have been used for predicting what extractive agents are likely to be effective in a given separation method have been described by L. Berg in an article published by Chem. Eng. Progress, Vol. 65, No. 9, pages 52-57, Sep. 1969; the contents of which are hereby incorporated by reference. In discussing extractive distillation, it was stated in the previously identified article that ". . . hydrogen bonds appear to be an important factor since all successful extractive distillation agents are highly hydrogen bonded liquids. Thus, the criteria for successful extractive agents are that they boil considerably higher than the compounds being separated, form no minimum azeotropes with the components, and be a highly hydrogen bonded liquid, that is, Class I or Class II of the hydrogen bond classification. Phenols, aromatic amines (aniline and its derivatives), higher alcohols, glycols, etc. are examples of successful extractive agents."